Anomalous heat conduction in one dimensional momentum-conserving systems
We show that for one dimensional systems with momentum conservation, the thermal conductivity $κ$ generically diverges with system size as $L^{1/3}.$
cond-mat.stat-mech↗
arXiv subjects
Onuttom Narayan
Publications and source records attributed to Onuttom Narayan.
Convergence of Monte Carlo Simulations to Equilibrium
We give two direct, elementary proofs that a Monte Carlo simulation converges to equilibrium provided that appropriate conditions are satisfied. The first proof requires detailed balance while the second is quite general.
cond-mat.stat-mech↗
Anomalous scaling in depinning transitions
It is demonstrated that the renormalization group (RG) flows of depinning transitions do not depend on whether the driving force or the system velocity is kept constant. This allows for a comparison between RG results and corresponding self-organized critical models. However, close to the critical point, scaling functions cross over to forms that can have singular behavior not seen in equilibrium thermal phase transitions. These can be different for the constant force and constant velocity driving modes, leading to different apparent critical exponents. This is illustrated by comparing extremal dynamics for interface depinning with RG results, deriving the change in apparent exponents. Thus care has to be exercised in such comparisons.
cond-mat↗
Vector lattice model for stresses in granular materials
A vector lattice model for stresses in granular materials is proposed. A two dimensional pile built by pouring from a point is constructed numerically according to this model. Remarkably, the pile violates the Mohr Coulomb stability criterion for granular matter, probably because of the inherent anisotropy of such poured piles. The numerical results are also compared to the earlier continuum FPA model and the (scalar) lattice $q$-model.
cond-mat↗
Self similar Barkhausen noise in magnetic domain wall motion
A model for domain wall motion in ferromagnets is analyzed. Long-range magnetic dipolar interactions are shown to give rise to self-similar dynamics when the external magnetic field is increased adiabatically. The power spectrum of the resultant Barkhausen noise is of the form $1/ω^α$, where $α\approx 1.5$ can be estimated from the critical exponents for interface depinning in random media.
cond-mat.stat-mech↗
Flux penetration in slab shaped Type-I superconductors
We study the problem of flux penetration into type--I superconductors with high demagnetization factor (slab geometry).Assuming that the interface between the normal and superconducting regions is sharp, that flux diffuses rapidly in the normal regions, and that thermal effects are negligible, we analyze the process by which flux invades the sample as the applied field is increased slowly from zero.We find that flux does not penetrate gradually.Rather there is an instability in the process and the flux penetrates from the boundary in a series of bursts, accompanied by the formation of isolated droplets of the normal phase, leading to a multiply connected flux domain structure similar to that seen in experiments.
cond-mat.supr-con↗
Dyson's Brownian Motion and Universal Dynamics of Quantum Systems
We establish a correspondence between the evolution of the distribution of eigenvalues of a $N\times N$ matrix subject to a random Gaussian perturbing matrix, and a Fokker-Planck equation postulated by Dyson. Within this model, we prove the equivalence conjectured by Altshuler et al between the space-time correlations of the Sutherland-Calogero-Moser system in the thermodynamic limit and a set of two-variable correlations for disordered quantum systems calculated by them. Multiple variable correlation functions are, however, shown to be inequivalent for the two cases.
cond-mat↗